Method for rapid low-salted pickling of aquatic product

Abstract

A method for rapid low-salted pickling of aquatic products is disclosed, which includes preliminary processing of raw materials, bacteria-reducing treatment of plasma activation gas, marinade adding and plasma treatment, cyclic bacteria-reducing treatment with the plasma activation gas and vacuum pickling. The marinade adding and plasma treatment include respectively injecting the marinade and plasma working gas into a tumbler, with a flow rate of ionic working gas injected into the tumbler of 1.5-2 L/min and a flow rate of a pickling solution of 0.5-0.8 L/min: and at the same time, starting a plasma power supply, and performing low-temperature plasma treatment on the aquatic products to be pickled, with a plasma treatment voltage of 12000-15000 V, a current of 60-80 mA, a frequency of 8-10 kHz, which is a second bacteria-reducing treatment, with plasma treatment time of 15-20 min.

What is claimed is: 
     
       1. A method for rapid low-salted pickling of aquatic products, wherein the method adopts a device for rapid low-salted pickling of aquatic products, the device comprises a pickling device, a plasma system, a gas circulation system, and a material pretreatment bucket; the pickling device comprises a tumbler and a vacuum pump; the plasma system comprises a plasma generating device, a plasma power supply and a controller; the gas circulation system comprises a gas inlet, a gas inlet pipe, an extraction fan, an extraction pipe, a gas treatment device, and an exhaust fan;
 wherein the tumbler has a marinade inlet for introducing a pickling fluid, wherein the gas inlet is for introducing a plasma feeding gas, the introduced pickling fluid and plasma feeding gas are sprayed by a nozzle through the gas inlet pipe, and then uniformly distributed on surfaces of the aquatic products to be pickled through the plasma generating device, 
 wherein the extraction fan is fixed at an inner position of a bucket cover of the tumbler, and is connected with the gas treatment device through a vacuum interface/gas outlet in the middle of the bucket cover, the concentrations of nitrogen, oxygen, and ozone in a plasma active gas are monitored and controlled by the gas treatment device; 
 wherein the exhaust fan comprises a first exhaust fan and a second exhaust fan, the first exhaust fan is fixed at an inner position of the bucket cover of the tumbler, and is connected with the gas treatment device through the vacuum interface/gas outlet in the middle of the bucket cover, and the second exhaust fan is arranged on a side of the gas treatment device away from the tumbler and connected with the extraction pipe, and the extraction pipe is divided into two branches, one of which is communicated with the material pretreatment bucket of the aquatic products before pickling, and the other of which is communicated with the extraction fan at the gas inlet; 
 wherein the method comprises:
 1) preliminary processing of raw materials, wherein the preliminary processing comprises: removing inedible parts of the aquatic products to be pickled, cutting them into pieces after cleaning, and putting the pieces into the material pretreatment bucket; 
 2) bacteria-reducing treatment with the plasma active gas, in which the plasma active gas is introduced into the material pretreatment bucket to perform a first bacteria-reducing treatment on the aquatic products to be pickled; 
 
 at the same time, starting the plasma power supply and non-thermal plasma treatment on the aquatic products to be pickled, with a plasma treatment voltage of 12000-15000 V, a current of 60-80 mA, and a frequency of 8-10 kHz, wherein the first bacteria-reducing treatment is conducted for 15-20 min;
 3) marinade adding and plasma treatment, comprising: 
 
 putting the aquatic products which have been subjected to the first bacteria-reducing treatment into the tumbler; 
 injecting the pickling fluid into the tumbler, wherein the flow rate of the pickling fluid is maintained at 0.5-0.8 L/min; injecting a plasma feeding gas into the tumbler, wherein the flow rate of the feeding gas is maintained at 1.5-2 L/min, this is a second bacteria-reducing treatment, with a treatment time of 15-20 min; and
 4) cyclic bacteria-reducing treatment with the plasma active gas, in which after the second bacteria-reducing treatment is finished, gas valves between the extraction pipe and the material pretreatment bucket are closed, the extraction fan and the exhaust fan are turned on, and then the plasma active gas extracted from inside of the tumbler is passed through the exhaust fan, the gas treatment device and the gas inlet to re-enter into the tumbler to form a gas circulation driven by the extraction fan and the exhaust fan, and this is a third bacteria-reducing treatment, with a treatment time of 20-30 min; and 
 5) vacuum pickling, in which after the third bacteria-reducing treatment is completed, the vacuum interface/gas outlet at the bucket cover of the tumbler is connected with the vacuum pump and the tumbler is vacuumized, and the tumbler is kept being rotated to vacuum pickle the aquatic products therein for 2-3 hours, with a vacuum degree of 0.05-0.20 MPa and a rotating speed of 4-10 r/min. 
 
 
     
     
       2. The method for rapid low-salted pickling of the aquatic products according to  claim 1 , wherein conditions of the first bacteria-reducing treatment in step 2) are the same as those of the second bacteria-reducing treatment in step 3). 
     
     
       3. The method for rapid low-salted pickling of the aquatic products according to  claim 1 , wherein the pickling fluid consists of 20-30 parts of salt, 5-8 parts of potassium chloride, 1.5-4.5 parts of citric acid, 20-30 parts of white wine, 1-2 parts of fennel powder, 3-5 parts of pepper powder and 470-500 parts of water, by weights. 
     
     
       4. The method for rapid low-salted pickling of the aquatic products according to  claim 3 , wherein the pickling fluid is in a sterile environment with final salt content less than 12 wt. %. 
     
     
       5. The method for rapid low-salted pickling of the aquatic products according to  claim 1 , wherein the plasma feeding gas is one or any combination of air, nitrogen, oxygen and argon. 
     
     
       6. The method for rapid low-salted pickling of the aquatic products according to  claim 1 , further comprising step 6) and step 7) after step 5), wherein the step 6) and the step 7) comprise:
 6) sampling and cleaning, in which after the pickling is finished, the pickled aquatic products are taken out, clean water is injected into the tumbler through a marinade inlet and the tumbler is rotated to clean the tumbler; and 
 7) drying and packaging, in which the pickled aquatic products are dried by a heat pump, and the dried aquatic products are vacuum packaged to obtain vacuumed aquatic products. 
 
     
     
       7. The method for rapid low-salted pickling of the aquatic products according to  claim 1 , wherein the gas inlet pipe is a hollow pipe composed of two tubes and the gas inlet pipe extends to the inside of the tumbler through a rotating roller, an outer end of the gas inlet pipe is provided with the gas inlet, and the marinade inlet is provided beside the gas inlet, and a plurality of gas outlets are provided at a part of an interior of the tumbler, the nozzle is provided at each of the gas outlets, and each nozzle is directly below the plasma generating device. 
     
     
       8. The method for rapid low-salted pickling of the aquatic products according to  claim 1 , wherein the plasma generating device is a non-thermal plasma generating device, and is connected with the plasma power supply and the control system by wires passing through the gas inlet pipe. 
     
     
       9. The method for rapid low-salted pickling of the aquatic products according to  claim 1 , wherein the gas treatment device comprising a nitrogen and oxygen adsorption device, a nitrogen and oxygen detector, an ozone decomposition device and an ozone concentration detector. 
     
     
       10. The method for rapid low-salted pickling of the aquatic products according to  claim 1 , wherein the non-thermal plasma treatment is performed while the pickling fluid is injected into the tumbler.